As an example of an optical transmission technology, there is an optical transport network (OTN) transmission technology. In the OTN transmission technology, for example, a plurality of low-speed signals called LO-ODU signals are multiplexed (may be referred to as “mapped”) in (to) a higher-speed signal called an HO-ODU signal (or OTN signal), and transmission of the HO-ODU signal is performed.
The reception side of the HO-ODU signal de-multiplexes (may be also referred to as “de-maps”) the plurality of LO-ODU signals that have been multiplexed in the received HO-ODU signal. Here, “LO-ODU” is abbreviation of “low order-optical data unit”, and “HO-ODU” is abbreviation of “high order-optical data unit”.
The HO-ODU signal may be referred to as “high-speed signal”, “high-order signal”, or “upper layer signal”, and the LO-ODU signal may be referred to as “low-speed signal”, “low-order signal”, or “lower layer signal”.
Japanese Laid-open Patent Publication No. 2012-209754 is a related art.